Specific gravity recorder



, cgt. 12', 194s'.

J. R. MARTIN ETALv 2,451,036 sPEcIFIc GRM/HY RECORDER Filed Sept.- 30, 1944 3 Sheecs--Sl'xeet 1 X 4 Y l -l BY@l Z J ATTORNEY.

Oct; 12,1948. J. Rf MARTIN ET AL 2,451,036

SPECIFIC GRAVITY 'RECORDER l Filed Sept. 30, 1944 I 3 Sheets-Sheet 2 v WMINVENTORS. F 6; gm/

figg/MM Oct. 12, 1948. i J. R. MARTIN ErAL 2,451,036

' SPECIFIC GRAVITY RECORDERl Filed Sept. 30, 1944 3-Sheets-Sheet 3 gy fR/M gn/ INVENToRs. maf 5M @j M@ y ATTORNEY.

' atmospheric conditions.

Patented Oct. 12,A

SPECIFIC GRAVITY RECORDER John R. Martin and Forrest B. Burrell, Baytown,

Tex.,\assignors to Standard Oil Development Company, a corporation of Delaware Application September 30, 1944, Serial No. 558,534

(Cl. i3-33) 'l Claims. 1

The present invention is directed to a device for indicating or recording the specic gravity of a moving stream of liquid.

In the handling of flowing liquids, it is irequently desirable for control purposes or distribution purposes to have a continuous record or indication of the speciilc gravity of the liquid as it exists in the owing stream without withdrawing a sample. The .usual method for determining specific gravity comprises withdrawing 'a sample from the stream of' interest and then, by means of suitable hydrometers or other instruments, determining its weight in relation to an equal volume of water. In certain refinery operations where relatively heavyhydrocarbons are mixed with liquefied normally gaseous hydrocarbons, such as propane, it is diiiicult to determine the specic gravity of the mixture by usual methods and it is necessary tov resort to time-consuming expensive operations.

The periodic determination of specific gravity generally is of little or no value as far as indicating this property of aliquid undergoing processing, especially in dealing with liquids at temperatures and pressures which materially diier from More particularly, the usual methods of determining the specic gravity of mixtures are not suitable or applicable to mixtures that arerapidly undergoing a physical or chemical change since the withdrawn sample materially diiers from the sample at the instant o! its withdrawal. Likewise, the liquid in its ilowing state may comprise` a mixture of vapors and liquids in which case the analysis oi' a withdrawn sample would fail to indicate the specific gravity obtaining under the conditions during the proc-` essing operations. For these and other reasons, it is highly desirable to employ an apparatus which is capable of indicatingv or recording the specific gravity of a liquid undergoing processing under the temperature and pressure conditions encountered in the processing operation. A constream. An additional vention is to provide an apparatus which will accurately -and rapidly indicate and record the changes in speciilc gravity of flowing liquid that is undergoing definite processing operations, particularly such liquids as may contain dissolved gases. A further object oi' the present invention is the provision oi' apparatus of the type described including a system of levers so arranged that the moving parts are protected from the action of the liquid, the speciilc gravity of which is being indicated or recorded.

Another object of the present invention is the provision oi' a device of the character described in which are disposed two bodies of liquid the one being the liquid under observation and the other being a non-corrosive, non-fouling liquid immiscible with the liquid under observation which may be referred to as a sealing liquid and in lwhich the moving parts of the apparatus are immersed in the sealing liquid.

Further objects and advantages of the present invention will appear from the following detailed description of the accompanying drawing in 2li which Fig. 1 is a vertical section through one embodiment. oi the present invention;

Fig. 2 is a horizontal section along line XY of Fig. 1;

Fig. 3 is a detail of a supporting bracket included in the device of lligl 1;

Fig. 4 is a detail of the shaft for transmitting motion from the interior to the exterior of lthe vessel shown in Fig. 1; and,

Fig.5 is a vertical section of a modiilcation of the embodiment shown in Fig. 1.

tinuous indication or record of the specic gravity l oi' a iluldunder actual operating conditions serves as a valuablemens for controlling particular operations.

An object of the'present invention is to provide an apparatus for continuously indicating or recording the specific gravity of a flowing stream of liquid under the conditions obtaining in the stream of liquid, the speciilc gravity of which is to be measured. At the upper end ofthe vessel is an outlet 3 for the stream oinliquid. A second outlet 4 for said stream is provided on the side of the vessel at a point below theinlet point. At a suitably spaced point below outlet I there is arbiect of the present infine the interface between the liquid of the flow-- ing stream and a sealing liquid hereinafter more specifically referred to.

At the bottom of vessel I there is xed an open topped receptacle 6. This receptacle is lled to a suitable height with a body of reference liquid 1 which may suitably be mercury, although other liquids immiscible with the sealing liquid may be employed. For the purpose of introducing this reference liquid into receptacle 6 there is provided in the Wall of vessel I an inlet 8 conveniently arranged to permit the insertion of a tube for conducting liquid from the exterior of vessel I into the receptacle. The bottom of the receptacle is provided with an opening 9 which extends through the bottom of the vessel I and is provided with threads I to receive a plug. This opening permits the draining of the receptacle.

Partially immersed in the reference liquid 1 is a float I I having rigidly attached to its upper sur-l face a vertical stem I2. This stem is pivoted at its upper end to a lever I3 which is mounted on a fulcrum I4 in such a way as to rotate about the fulcrum but to be capable of no other movement relative to the fulcrum.

To the other end of lever I3 is pivoted one end of a-link I5, the other end of which is pivoted to an intermediate point of a lever I6, one end of which is fixed for rotation about fulcrum I1 and the other end of which is pivoted to a vertical s tem I8 fixed to the bottom of a float I9. To the upper end of float I9 is xed another vertical stem 20 which passes through and is guided in a central opening 2| `of a disc 22 screw threadedly engaged in the outlet 3, said disc being provided with a series of passages 23 to permit the passage of the liquid.

The float I9 is so arranged that in its lowermost position its bottom will be above the interface between the flowing stream of liquid and the sealing liquid. The sealing liquid may be any liquid which is immiscible with the liquid in the flowing stream and which will not foul or corrode the moving parts of the lever system. As.

heretofore mentioned, it must also be immiscible with the reference liquid 1. It may be introduced into the system, as required, with the test liquid in so far as it does not emulsify with the latter under the conditions of flow. A separate inlet for this liquid may be provided, if desired. The use of this' sealing liquid is of a special advantage in the handling` of asphaltic oils in the gravity recorder because these oils tend to deposit asphalt in gummy material on the joints of the lever system introducing errors. It is also of great importance when the liquid stream, the gravity of which is being measured, is corrosive to common metals. For the handling of such a liquid only the float I9 and its stems I8 and 20 need be composed of usually more expensive resistant metals and the remainder of the moving system immersed in the sealing liquid may be composed of cheaper materials.

Fixed to the bottom of the vessel I are a pair of brackets 24. Each of these brackets in side view has the form of an h, as shown in Fig. 3, and a top view has the shape of a letter L, as shown in'Fig. y2. At-the lower end of each leg of the h is a tongue 25 providedwlth a hole to receive a bolt or rivet for fastening the bracket to the bottom of the vessel I. 'I'hese brackets are oppositely disposed to each other with their long legs in parallel to and in alignment with 4 each other. The bottoms of the small legs are fixed to the bottom of the vessel I on either side of the receptacle 6 so that the upper ends of the small legs overlie said receptacle. The upper ends of the small legs are provided with holes in which are journalled a pin constituting fulcrum I4. The upper ends of the long legs are also each provided with a hole to receive a pin constituting fulcrum I'I.

Extending chordially through the wall of the vessel I is a cylindrical barrel 26 having its axis perpendicular to the plane of the h-shaped brackets. The inner end of said barrel, as shown in Fig. 4, has clamped to it by clamping member 21 an extension arm 28 of which the clamp 21 is an integral part. The outer end of the extension arm carries a block 29 provided with a bearing screw 30 at its center to receive one end of a pintle 3I which extends axially to the other end of a cylinder 26 where it is journalled in a second bearing screw 32. The' pintle 3I has formed integrally with it a small diameter shaft 33 which extends through the bearing screw 32, which is also a sealing plug, beyond the end of cylinder 26. 'I'he outer end of the plug 32 is provided with a packing gland `35. Fixed to the outer end of the shaft 33 is an indicating or recording arm 36 carrying at its free end a stylus 31.

As shown in Fig. 2, there is welded to the side of the vessel I a flat -base 38 to which is fixed a case 39 containing clock Work which operates a chart 40 iixed to a stub shaft 4I protruding through the case 39. The stylus 31 is arranged to move on the chart 40. in the manner commonly known in recorders of this type. Usually the chart will be calibrated to produce in conjunction with the stylus a record of variation in gravity with time. Y

Fixed to the pintle 3| between the inner end of cylinder 2B and the block 29 is a metal arm 42 carrying at its free end a roller 43. This arm is mounted so as to lie with its longitudinal ,axis in the same plane as that of lever I6 with the roller 43 riding on the lever I6. Thus, arm 42 moves in response to movements of lever I6 about its fulcrum I1 and this motion is imparted to the pintle 3I and thus to the recorder.

. In order to prevent to the maximum extent turbulent o'w around the float I9 and the buoying of float I9 by stream velocity, the inlet port 2 is provided with an inlet nozzle 44 which is blocked off on its inner end and is provided with oppositely disposed openings 45 on its horizontal axis. This arrangement results in the impartation to the incoming liquid of a tangential direction of ow. This particular type of inlet is advantageous when the specific gravities of liquids having a high velocity of flow are being measured. In some cases it may be advantageous to arrange suitable baffles in the upper end of vessel I to insure uniform mixing ofA the liquid in this portion of the vessel.

In order to impart additional stability to the movement of the float I I, there may be provided a link 46 pivoted to a clamp 41 fixed to the edge of receptacle 6 and also pivoted to float II. In the event the pivoted link 46 is employed, its pivot point on the clamp 41 should, preferably, be vertically in line with fulcrum I4, in order to prevent the application of side thrust to float II.

Alternatively, suitable guides may be provided for s liquid of substantially constant density with which the density of the liquid under test may be compared: hence the specific gravity of the liquid under test relative to the reference liquid can be measured and the specific gravity relative to any other liquid can be determined. It will be understood, also, that the reference liquid 'I and float II partially submerged therein 'provide a reference force to counterbalance the force developed by changes in buoyancy of float I in the liquid whose specific gravity is to be measured. lit will be seen that lever I3 and link Il cooperate to apply the reference force in' opposition to the force developed by float I8. Thus,

when oat I8 moves upwardly, as rwhen a liquid of high specific gravity relative to the lower range of the instrument is introduced into chamber I,

4. The reference liquid is, for purposes of example, mercury.

stem Iii rises and. through the' operation of lever I8, link I5 and lever I8, causes float II to be forced downward into reference liquid 1. Since the density of reference liquid 'I remains constant, the buoyancy of float II in liquid 'I does not change and, accordingly, the forced immersion of the float sets up a force which reacts through the crore-mentioned leversand link to counteract, at least in part. the upward movement of float I9. Similarly, when -fioat I9`tends 5. The mercury iioat and the mercury chamber are both considered to be cylindrical.

The following symbols are used throughout the .l computations:

a=the distance, infeet, from the center of fixed fuicrum i1 to the. center of the -pivot between I3 and I8 (see drawing).

b=the distance, in feet, from the center of fixed fulcrum I'l to the center of the pivot between link I5 and-lever I8.

c=the distance, in feet, from the center of fixed fulcrum I4 to the center of the pivot between link I5 and lever I3. v

d= the distance, in feet, from the center of fixed fulcrum It to the center of the pivot betwee lever I3 andstem I2. v g

D -the outside diameter, in feet, of the mercury float II. l

D1=the inside diameter, in feet, of the mercury chamber 6.

I Fi=the upward force, in pounds, exerted on the non-aqueous liquids which are immiscible with oil may be employed and water itself may be employed if the moving parts are made of nonrusting alloy.

In Fig. 5P is shown a modication which may be employed when the specificv gravity of the liquid in the owing stream is greater than that of the sealing liquid. Here, for example, the liquid in the flowing stream may be an aqueous solution in which case the sealing liquid 5l may be `any suitable hydrocarbon such as kerosene. In general, in this modification the position of the parts shown in Fig. 1 is simply reversed. Farts in Fig. 5 corresponding with parts in Fig. 1 bear the same numerals. The mountings for the moving parte are brackets similar to those shown in Fig. 1 attached to the cover 48 of the vessel. Alternatively, suitable brackets can be aiiixed to the wall of 'vessel i itself for the support of the various moving parts in the lever system, as well as for the support 'of receptacle 6. The operation of this modication is believed to be evident from the described operation of the embodiment shown in Fig. 1 without the need for further detailed description. With reference to Fig. 1 the following calculations'demonstrate the manner in which the proportions of the various elements of thel system enter into the response of the system 'to changes in gravity in the flowing liquid under observation and may serve as a guide to the design and calibration of such a system. In making these calculations the following assumptions are made: v

1. The friction of the bearings is zero. 2. The weight ofthe lever linkage is zero.

mains constant.

lever linkage by the measuring float I9 Iwhen the latter is submerged in a liquid of density Fz=the resultant downward force, in pounds,

exerted on the mercury float I I when Fi is exerted by the measuring float I9.

Fa=the `upward force, in pounds, exerted on the lever linkage by the measuring float I9 when the latter is submerged in a liquid of density G2..

F4=the resultant downward force, in pounds, exerted on the mercury float II when Eb is exerted by the measuring float I 9.

Gi=the density, in pounds per cubic foot, of the lightest liquid sample to be measured by the instrument.

G2 =the density, in pounds per cubic foot, of the heaviest liquid sample to be measured by the instrument.

Gz--G1=AG=the density range of the instrument.

Gm=the density, in pounds per cubic foot, of

mercury.

G=the density. in pounds per cubic foot, of the immiscible sealing liquid 563.

Hlthe total length, in feet, ofthe mercury float hi=the length, in feet, of they mercury neat Il submerged in mercury when the measuring float 'Is is submerged in a liquid ofdensity G1.

liz-:the length, in feet, ofthe mercury floaty il submerged in mercury when the measuring float I9 is submerged in a' liquid of density G2.

h2-hi=the leffective travel, in feet, of the mercury level on the mercury iioat I I as the density of the measured liquid changes from G2 to G1.

L1=the travel, in feet, of the measuring float I9.

Lz=the travel, in feet, of the mercury float II.

V1=the volume, in cubic feet, of the measuring float I9.

V2=the volume, in cubic feet, of the mercury oat Il submerged in mercury when F3 is exerted by the measuring float I9,

V3=the volume, in cubic feet, of the mercury float II submerged in mercury when F3 is exerted by the measuring float I9. v V4=the volume, in cubic feet, f the mercury float Il submerged in the sealing liquid when F1 is exerted by the measuring float I9. Vs=the volume, in cubic feet, of the mercury float II submerged in the sealing liquid when F: is exerted by the measuring float I9.

W1=the weight, in pounds, of the measuring.

fioatll s W2=the weight, in pounds. of the mercury noat computations Since forces exerted by the measuring float must balance those exerted on the mercury oat the following relations exist:

Volumes of various portions of the mercury float are as follows:

2 2 VFX (H-hl) VFXGI-hi) Substituting these values in (4) 5 The travel of the measuring and mercury floats are related by the following expressions:

Substituting the latter value in (7) Substituting (8) in (5) EXT and simplifying Fr'om Equation 9 it is possible to calculate the specific gravitymeasuring range of any instrument designed according to this invention after the following physical measurements have been determined:

(1) Lengths of the levers (2) Allowable travel of the measuring float (3) Volume of the measuring float (4) Diameters of the mercury float and mercury chamber (5) Density of the sealing liquid Likewise, it is possible to calculate any one required physical measurement for an instrument -designed to measure a desired specific gravity range by substituting in the above equation arbitrarily selected values for the other physical dimensions.

It will be apparent that many changes in the conguration and arrangement of parts canbe made without departing from the scope of the present invention. A wide variety of lever systems can be adapted to the apparatus described. The essential feature is that the moving system :must be immersed in a sealing liquid of the character heretofore described,

As the mercury float I I moves through its full range of travel, the mercury level will change depending upon the relative diameters of the mercury float and the mercury chamber 6. These relations are expressed as follows:

Expanding the left-hand side of l(6) and simplfying DL3= (hz-h1) (D12- D2) The nature and objects of the present invention having been thus described and illustrated. what is claimed as new and useful and is desired to be secured by Letters Patent is:

1. In a device for continuously measuring the specific gravity of a flowing stream of liquid, a chamber having a portion adapted to retain a reference liquid, a float mounted to be partially immersed in said reference liquid, an inlet port on said chamber for the test liquid. the gravity of which is to be measured, an outlet port for said test liquid arranged so as to maintain a predetermined body of said test liquid in said chamber, a float arranged to be totally immersed in said test liquid, a lever system arranged within said chamber between said floats, said floats being connected to said lever system in opposition to each other, means for indicating the resultant of the motion of said lever system, and means for maintaining said lever system completely envel- 'oped in a sealing liquid immiscible with said reference liquid and with said test liquid.

2. In a device for continuously measuring the specific gravity of a flowing stream of liquid, a chamber having a portion adapted toretain a 75 reference liquid, a float mounted to be partially immersed in said reference liquid, an inlet` Port on said chamber for the test liquid, the gravity oi.' which is to be measured, an outlet port for said test liquid arranged so as to maintain a pre-determinedbody of said test liquid in said chamber, a float arranged to be totally immersed in said test liquid, a lever system arranged between said inlet port for said test liquid and the portion of said chamber containing said reference liquid, said floats being connected to said lever system in opposition to each other, means for indicating the resultant of the motiony of said lever system and ports arranged on said'chamber between said inlet port for the test liquid and the portion of said chamber containing the reference liquid for the maintenance in said chamber of a layer of sealing liquid immiscible with said reference liquid and with said test liquid and of a thickness suilicient to envelop said lever system.

3. In a device for continuously measuring the specic gravity of a ilowing stream of liquid, a chamber `having a portion adapted to retain a reference liquid, a float mounted to Ibe partially immersed in lsaid reference liquid, an inlet port on said chamber for the test liquid, the gravity of which is to be measured, an outlet port for said test liquid arranged so as to maintain a pre-determined body of said test liquid in said chamber, a oat arranged to be totally immersedin said test liquid, a lever system arranged within said chamber between said floats, said iloats be-`I ing connected to said lever system in opposition to each other, means for transmitting the resultant of the motion of the lever system to the exterior of said chamber and means for maintaining said lever system completely enveloped in a sealing liquid immiscible with said reference liquid and with said test liquid.

4. In a device for continuously measuring the specific gravity of a flowing stream of liquid, a

a lever system arranged out of contact with said e said chamber, a iloat mounted to be partially im- 0 mersed in said body of liquid, means for transmitting the resultant of the motion of such system of levers to the exterior of said chamben'an inlet port for the test liquid on said chamber at a point above the level of said body of liquid, 'an outlet port for said test liquid arranged so as to maintain the upper portion of said chamber full of said test liquid, a iloat arranged to be totally immersed in said test liquid in the upper part of said chamber, and means connecting the two floats to said lever system in opposition to each other.

7. In a Adevice for continuously measuring the specific gravity of a flowing stream of liquid, a chamber having a portion adapted to retain a reference liquid, a irst fioat mounted to be partially immersed in said reference liquid, an inlet port on the chamber for the test liquid the gravity of which is to be measured, an outlet oport for said test liquid arranged so as to maintain a predetermined body of said test liquid in said chamber, a second iioat vertically spaced from the .rst float and arranged to be totally immersed in said test liquid, a lever system arranged within said chamber between said iloats. and means for maintaining said lever system completely enveloped in a sealing liquid immiscible with said reference liquid and with said test liquid, said floats being connected to said lever system in opposition to each other and means for indicating liquid, said iloats being connected to said lever system in opposition to each other, means i'or transmitting the resultant oi' the motion of the lever system to the exterior of said chamber and reference liquid, an inlet port on said chamber for the test liquid, the gravity of which is to be measured, an outlet port for said test liquid arranged so as to maintain a pre-determined body oi' said test liquid in said chamber, a noat arranged to be totally immersed in said test liquid,

The following references are oi' record'in the ille of this patent:

UNITED STATES PATENTS.

Number Name Date j 1,424,403 Hartman et al Aug. 1, 1922 1,450,023 Edelman Mar. 27, 1923 1,546,702 ,Bailey July 21, 1925 1,604,387 Caldwell Oct. 26, 1926 1,800,532 Howard Apr. 14, 1931 2,248,322 Annin July 8, 1941 2,251,771 Wynn et al. Aug. 5, 1941 2,279,254 Irwin Apr. '1, 1942 FOREIGN. PATENTS y Number Country \Date 66,271 Germany Dec. 20, 1892 184,789 Great Britain ap'r. 12,v 192s 

